Milrinone Dosing in Neonates and Pediatric Patients
For neonates and pediatric patients with cardiac dysfunction, milrinone should be administered with a loading dose of 50 mcg/kg given over 10-60 minutes, followed by a continuous infusion of 0.25-0.75 mcg/kg/min, with dose adjustment based on renal function. 1, 2
Dosing Recommendations
Standard Dosing
- Loading dose: 50 mcg/kg IV infused over 10-60 minutes
- Maintenance infusion:
- Minimum: 0.375 mcg/kg/min
- Standard: 0.5 mcg/kg/min
- Maximum: 0.75 mcg/kg/min
Dosing in Renal Impairment
Milrinone is primarily excreted unchanged in the urine, requiring dose adjustment in renal dysfunction:
| Creatinine Clearance (mL/min/1.73m²) | Infusion Rate (mcg/kg/min) |
|---|---|
| 5 | 0.2 |
| 10 | 0.23 |
| 20 | 0.28 |
| 30 | 0.33 |
| 40 | 0.38 |
| 50 | 0.43 |
For patients with severe renal impairment (CrCl ≤30 mL/min/1.73m²), reduce loading dose to 25 mcg/kg and maintenance infusion to 0.25 mcg/kg/min 3.
Special Considerations for Neonates
Neonates and young infants may have immature renal function and altered pharmacokinetics. Recent research suggests:
- Developmental changes in clearance must be considered in neonates 4
- For neonates with acute kidney injury (AKI) following cardiac surgery, dose adjustment based on AKI stage is recommended 4
- Target therapeutic concentration range: 100-300 ng/mL 3
Clinical Applications
Milrinone is indicated for:
- Cardiogenic shock
- Congestive heart failure
- Post-cardiac surgery support
- Septic shock with myocardial dysfunction
Administration Guidelines
Preparation:
- Dilute milrinone to a concentration of 200 mcg/mL using 0.45% NaCl, 0.9% NaCl, or 5% Dextrose
- Use a calibrated electronic infusion device for administration
Monitoring:
- Continuous cardiovascular monitoring is essential
- Monitor blood pressure, heart rate, cardiac output, and clinical signs of perfusion
- Assess renal function regularly
- Watch for adverse effects including hypotension, arrhythmias, and thrombocytopenia
Titration:
- Titrate dose based on hemodynamic response
- Duration of therapy depends on patient responsiveness
Potential Adverse Effects
- Hypotension (particularly with rapid loading dose)
- Ventricular arrhythmias
- Headache
- Thrombocytopenia (less common than with amrinone)
Practical Considerations
- Milrinone has both inotropic and vasodilatory effects (inodilator)
- Unlike catecholamines, milrinone does not significantly increase myocardial oxygen consumption
- In pediatric patients with septic shock, milrinone has been shown to increase cardiac index and decrease systemic vascular resistance 5
- Avoid rapid administration of loading dose to prevent hypotension
- Ensure adequate intravascular volume before initiating therapy
Common Pitfalls to Avoid
- Failure to adjust dose in renal dysfunction - Milrinone accumulation can lead to toxicity
- Inadequate monitoring - Continuous hemodynamic monitoring is essential
- Confusing with amrinone - Potential fatal complications if drugs or dosages are interchanged
- Rapid administration - Can cause significant hypotension
- Using in hypovolemic patients - Ensure adequate volume status before administration
Milrinone's hemodynamic effects typically begin within 5-15 minutes of loading dose administration, with peak effects seen at 1-2 hours. The drug's half-life is prolonged in renal dysfunction, necessitating careful dose adjustment in these patients.